Scrub the clams to clean their shells and drain excess water.

Soak vermicelli in water until softened, then drain and cut into manageable lengths. Separate celery leaves and stalks; peel stalks and slice into 1cm pieces, while chopping leaves into bite-sized pieces. Mince garlic after removing its core.

Mix all seasoning ingredients in a bowl.

Heat sesame oil and garlic in a pot over medium heat until fragrant. Add clams and stir briefly. Add vermicelli and sake, cover, and steam on low heat for 5 minutes until clams open.